The very best photographs of the sun ever yet seen have been taken at the Observatory, Meudon, near Paris, by Mr Janssen; and copies on glass, twelve inches diameter, are now placed in the hands of some of our scientific societies. They well repay study, for they shew distinctly the granular appearance of the sun’s surface: millions of white specks imbedded, so to speak, in a dense dark cloud. This surface is liable to violent commotions, or ‘vortex movements,’ as Mr Warren De la Rue calls them, ‘of which we can form no conception whatever in thinking of tornados on the earth’s surface. The photosphere,’ he continues, ‘had been whirled up in cloud-like masses in various parts of the sun; and he saw at once that that might be the origin of the luminous prominences with which we are all now so familiar.’ A conclusion drawn from these appearances is that sunspots are not the most important of solar phenomena. ‘There are changes taking place from day to day, from hour to hour, and in some cases from minute to minute, which completely change the aspect of the various parts of the sun, shewing an amount of activity which it is extremely necessary to study.’ And it is suggested that this could best be done by establishing a physical observatory devoted to ceaseless observation of the sun accompanied by photography. Such an observatory has been recently founded at Potsdam, near Berlin. Professor Wolf of Zurich has spent many years in collecting from every possible source records of sun-spots from the beginning of the seventeenth century, and the beginning of the telescope. And after careful examination he arrives at the conclusion that they do not bear out the theory of an eleven years’ period, for since 1610 there are twenty or thirty different maxima and minima, extending to sixteen years in some instances, and in others contracting to seven years. This is a fresh proof that many more observations are required for a settlement of the question.